It has become common practice to increase engine performance by turbocharging the engine. Among the various types of turbochargers are variable geometry turbochargers (VGT) wherein the swallowing capacity of the turbine is regulated by a governor to control the overpressure to fuel intake manifold. For a VGT controlled engine, it is critical to protect its turbocharger from over speeding. If the turbo speed is too high and exceeds its design limit, it may damage the turbocharger due to the over stress. In order to protect the turbocharger from over speeding, it is common practice to monitor the turbine, compressor or shaft angular velocity, i.e. the turbo speed.
Turbo speed sensors provide feed back to governors that regulate the swallowing capacity of the turbocharger. Certain turbo speed sensors are susceptible to electromagnetic (or radio frequency) interference (EMI). Vehicles typically include devices that generate EMI. EMI may contribute to less than optimal control of the turbo speed.